Dengue virus (DENV) is the most prevalent mosquito-borne virus causing disease in humans, with an estimated 2.5 billion people at risk of DENV infection, resulting in about 390 million annual infections worldwide. There are currently no licensed vaccines or specific therapeutics, and the death rate for severe dengue without proper supportive care can be over 20%. There are no immune competent animal models for dengue disease, which has made immune pathogenesis studies very challenging. The overall objective of this application is to develop a novel ex vivo human tonsil histoculture system to study DENV infection in the context of whole lymphoid tissue cytoarchitecture. In preliminary studies, we have demonstrated that human tonsil histocultures support a productive infection of WT DENV-2. By optimizing this histoculture system, we will work toward achieving our long-term goal of characterizing the infection of the all four serotypes of DENV in human tonsil histocultures, in which we can study the cell tropism, infection kinetics and immune responses of DENV in a more physiological context than existing cell-based systems.